Now, I know that the attenuation for my downstream line is good enough to go 20mbps. The problem is in the margin (SNR or noise). 15 give a stable 16mbps and it is demanded.

How much will the margin count decrease if I upgrade to 20mbps? And is it gonna be stable? <<< this is what the thread is all about.

The upload margin is 7 sure, but it is holding the 1mbps upload line very well, no problems at all, and the 20mbps package (same number for the download speed) also uses 1mbps upload speed so I believe the upload department is gonna be just fine. Unless it is still gonna be affected even though the change of speed will take place in the download side only!!!

db is the signal strength. If you start playing with settings in the box you could cause problems on the provider's network. Each box is uniquely identifiable so it would be simple to track you down.
If you're looking to go faster on your connection, do the honest thing and pay for it. I'm sure your ISP will be happy to take it...

This is what I have in mind. There is no other way in the first place.

I'm only making sure what the Downstream Margin will become at 20mbps having it 15db at 16mpbs as constant (fact) of the equation. The ISP will just upgrade it once requested. I don't want this to happen as I want the Margin to be no less than 8. This is why I made this thread. The ISP will still change it even of it goes down to 6 or 5.

I live in the 4th floor and electrical interferences seem to happen from time to time, dunno from where, and affect the signal causing disconnects.

Sorry if I implied doing an illegal act. I would never do that.

But I do appreciate you concern advising to do the right thing. I meant it.

Btw, speed from 8mbps to 20mbps here is a single package with the same price. It all depends on the availability.

in theory the ISP will say, now that the exchange is ADSL2+ capable we're selling 20Mb broadband.

regardless of the fact that there is so much noise that you'll never actually be able to get to that speed, and besides which the 20Mb number is all a bit pie in the sky anyway, hardly anybody actually sees those numbers, which is why they say "up to" in all the contracts etc.

Honestly you'd probably do well to speak to your neighbours and see if any of them have faster broadband or have upgraded etc and what experience they have had, or talk to the Telco with your concerns about noise etc.

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Yup, but to be honest, it is the actual gross speed we get. The problem is they act stupid that the speed does show on the modem what they promises while the final speed after losing all packets to reach the final transfer rate we see on the monitor is much lower than the numbers advertised. I get ~1.8MB transfer rate (that's like 14mbps) for my 16MB connection (16,380kbps as shown above) while it should according to adverts give ~2MB transfer rate; 16,380 kbps / 8 Bytes = 2047.5 MB/s.

A commercial trick to fill our heads up, but in actuality it is not really a trick at all.

I did all possible theoretical ways to presume the SNR for 20mbps and my final conclusion was 7.5 - 8db. Now I guess it is the practical way's turn. I'll ask them to upgrade the speed, try it for some time, then decide if it is good to keep. I can go back to 16mbps later no problem except for the time I'm gonna waste if it fails.

20mbps users here get ~2.3MB/s at best while in theory it should be ~2.5mbps; 20,480 kbps / 8 Bytes = 2,560 MB/s.

As for asking the ISP, I'm afraid they hired a bunch of losers to serve them the losers themselves. They can't ever distinguish between bit and byte most of the time. Here we have only a single ISP for xDSL can you believe that? No competition makes providers stupid and service bad.